Thermocouple testing apparatus



Wlay lg J. T, NUQHQLS THERMOCOUPLE TESTING APPARATUS Filed July l, 1951 2 Sheets-Sheet l Mimi/l @msnm/22 y @THT/M5 (2l/M JOHN 7 /V/C/v/OLS, @ff 1` Z J. "fr, www@ @@d .THERMOCOUPLE TESTING APPARATUS Filled July l, 1931 2 Sheets-Sheet 2 fig/f@ GREEN GREEN RED JO//A/ T. AOC/15,

FYROM-:TEE

Patented May 12, 1936 UNITED STATES PATENT OFFICE Claims.

'Ihislinvention relates to thermocouple testing apparatus and more particularly to` means for giving either a visual or audible alarm when a thermocouple circuit is rendered incomplete due 5 "toa break or extremely high resistance.

Heretofore no means has been provided for "l" notifying the operator of a break in a thermocouple circuit, therefore thermocouples have often been 'rendered inoperable with the result that l valuable material or apparatus has been serious'- ly damaged due tothe failure of controls dependent upon the thermocouple circuit.

In the drawings, Figure 1 is a diagrammatic showing of one form of apparatus for carrying out this invention.

l Figure 2 is a diagrammatic showing of a mod- Iilied form of apparatus for carrying out the invention.

Referring more particularly to Figure 1, the

zo numeral 2 designates a. source of loW voltage Used for operating the testing and alarm apparatus which may be in the form of storage batteries or any other suitable source of constant low voltage. The numeral 3 designates a thermocouple which may be mounted in any suitable furnace l'or the like.

"I'hethe-rinocouple 3 is adapted to alternately have its terminals 4 connected through a relay operated mechanism 5 to contacts 6 of a pyrometer or other suitable temperature registering means (not shown), and to the terminals 1 of a control and testing circuit to be described.

The relay 5 has one end of its coil 8 connected to one side of the source of low voltage 2 by a wire 9, and has its other end connected to the other side of the source of low voltage through a make and break device I0 and wire I2. The make and break device I0 is a cam-operated contact adapted to be alternately closed and opened by a cam I4 continually While the apparatus is in operation. When the make and break device III is closed a circuit is completed through the wire 9, coil 8 of relay 5, make and break device I3 and Wire I2, thereby energizing relay coil 8 and causing the core I5 of the rel-ay to move from left to right, thus disconnecting the thermocouple 3 from the contacts S of the pyrometer, and connecting the terminals of said thermocouple to the terminals 'l and Ia of the alarm and testing circuit to be described.

A second relay I'I is provided which has its coil I 6 normally energized by a circuit from the Wire 9 through the coil I3, and through wire I8 to the terminal 'Ia and thence through lingers I9 and I9 of the relay 5 and wire 20 to a linger 2| of a third relay 22, which is normally deenergized. From the lingers 2I of relay 22 the circuit continues through the spring or linger 23 of the relay 22, through wires 24, 25 and 26, back to Wire I2 and the other side of the source of current 2.

Immediately upon the operation of relay 5 the lingers or springs IIad and 4b of the relay 5 Will move out of contact with lingers or springs 6a and 6b and into contact with lingers or springs 3a and I9, respectively, thereby disconnecting the thermocouple 3 from the pyrometer terminals 6 and breaking the contact between lingers I9 and |92, so as to make a circuit as follows: from the wire 9 through the coil IB of relay I'I through Wire I8 and relay linger I9 to relay nger 4b, thence through the thermocouple 3 and back through the linger or spring 4a of relay 5 tothe linger or spring 3a and then through wire 2'I to Wires 25 and 26 to the opposite side of the source of current 2.

From the above it will be noted that the coil I6 of relay I1 is constantly energized as long as the thermocouple 3 remains intact, regardless of Whether the make and break device I0 is closed or open. As long as the coil I6 is energized finger or spring 29 Will be held away from the spring or linger 28.

Now, assuming that the thermocouple circuit should become open, due to a break in the thermocouple or to extremely high resistance, Which Would prevent the circuit being completed through the thermocouple, or for any other reason, then when the make and break device I0 closes, the circuit to the coil I6 of relay I1 will be incomplete so that fingers or springs 28 and 29 of the relay II will move together and complete a circuit through the coil 30 of the relay 22. The circuit thus completed through the coil 30 will be from the Wire 9 through the coil 30 through a Wire 3I and linger or spring 28 to and through the spring or linger 29, thence through Wire 26 back to Wire I2 and the other side of the source of current 2. The energization of coil 30 of relay 22 will cause its core 33 to move from the left to right, thereby moving its lingers or springs 23, 34 and 35 from left to right', so as to cause the lingers 34 and 35 to contact with springs or lingers 36 and 31, respectively, which will complete alarm circuits to the visible and audible alarms shown as red lights and bells 38 and 39, respectively.

When the relay 22 is deenergized the lingers or springs 34 and 35 will be in engagement with fingers or springs 40 and 4 I, respectively, so as to 59 to the wire56.

complete circuits to visible signals in the form of green lights 42 and 43, respectively.

It will be understood, of course, that any other form of visible or audible form of alarm other than the lights and bells shown and any combination of such signals may be used.

It will also be understood that circuits made and broken by the springs 34 and/or 35 may be used to operate valves or other control mechanisms (not showniwhen desired.

Referring more particularly to Figure 2, the apparatus therein shown consists of only two relays, which are designated by the numerals 50 and 5I, respectively, and the thermocouple is designated by the numeral 52.

The apparatus of the figure is adapted tobe operated from the usual power lines carrying 110 or other normal voltage, and, therefore, in order to provide a constant voltage for-the testing and alarm circuits a transformer 53 is provided between `power lines 54` and 55 and supply 1ines56 and 51 of the system.

The relaylBD is adapted to have its coil 58 alternately energized and deenergized' by a constantly operating make and break device 59.

When the make and break device 59 is closed a circuit is made from the wire 51 through" the coil`58 and through the make and break device Energization of the coil 58 of -relay50 will cause `the core 60 ofthe relay '50 =to move fromleft to right so as to break the connection between the relay springs or `iingers'iil `and 62 and `63 and 64, respectively, and 4make contactbetween the fingers or springs 6| andi65,vand63 and 66,respectively. As contact ismade between the fingers or springs 63 and66, a Contact:isbrokenbetweenthe spring or finger `IWandaspring or nger 61.

When the contactis made between the Aiingers 6| and 65 and 63 and 66, a circuit will be comlpleted from the Ywire 51 through a coil 5| of `relay 5l through a Wire69, thence through the ngers'66 and-63 and through thermocouple 52 `andiback Ithrough the iingers 6I and 65 to wires `69 and 10 to-the Wire 56 and to the other side of theline. Completion of the circuit through the coil 5| will energize the coil and cause the core 1|.offthefre1ay5l ytormove from left to right, thus making contact between ngers 12 and 13, 14 and 15, 16 and 1.1respectively, of the relay 5I. The .contacting of thefingers 14 and 15, 16 and 11 will `complete `circuits through visible signal lights 1B. vThe engagement of the fingers 12 and `13 Will complete a circuit from the wire 51 through the coil 5|a through the wire 68 `and ngers 66 and`61 (when relay 50 is deenergized), thence through a Wire 19 and fingers 12 and 13 to the wires and 56 and to the other side of the line.

From the .above it will be noted that if the coil 5I is once energized it will remain energized, regardless of whether the make and break device 59 is open or closed, as long as the circuit through the thermocouple 52 is complete, and therefore the green signal lights will remain lighted as long as the thermocouple circuit is complete.

If for any reason, such as a break in the thermocouple or high resistance, the circuit should be incomplete through the thermocouple 62, the coil 5M `will be deenergized when the make and break device 59 is closed to energize the relay 50 so as to make `the circuit through the thermocouple :52.

Immediately upon deenergization of the coil 5Iab of itherelay '5| the core 1l will move from right to left, and the fingers or springs 14 and 16 will contact with fingers 80 and 8i, respectively, so as to complete alarm circuits through visible and audible alarms shown as red lights BI and bells 82, respectively, thereby notifying the operator of a break in the thermocouple circuit.

It will be understood that the circuits made and broken by the fingers or springs 14 and 16 may-also be used to operate valves or other control mechanisms (not shown) when desired or necessary.

While I have shown` and described certain specific embodiments of my invention, it will be understood that rdo not Wish to be limited to the-detailsthereof, since various modications and changes may be made and will readily suggest themselves to those skilled in the art when adapting this invention to the various uses to which it may be put, without departing from the scope oi my invention, as defined in the appended claims.

I claim:

`1.` The combination of a device that conducts electricity when in operative condition, a circuit for said device, a normally closed test circuit, means for periodically disconnecting said device from the first named circuit and connecting it in said test circuit so that the latter remains closed while' so doing, circuit making-and-breaking contacts and means controlled by said test circuit for operating said contacts.

2. "I'hecombination of a device that conducts electricity when in operative condition, a circuit i for said device, a normally closed first circuit including a'first relay, a switch device held open by said first relay when the latter is energized and adapted to close when the latter is deenergized, a second circuit including 'a second relay, means for periodically energizing said second relay, a third circuit including said rst relay, and means including said second relay for disconnecting `said device from its circuit and connecting it in said third circuit and for opening said rst circuit shortly thereafter.

3. The combination of a thermocouple, a pyrometer, a circuit for interconnecting said thermocouple and said pyrometer, a relay including an operating coil, a source of electric energy, a circuit for connecting said thermocouple and said coil inseries with said source, a circuit for connectingsaid coil in series with said source, circuit making-and-breaking contacts for each of said circuits, and means Vfor operating said contacts so that the first and second named circuits are respectively broken and made and so that the third `named circuitis subsequently broken.

4. The combination of a thermocouple, a pyrometer, `a circuit for interconnecting said thermocouple and said pyrometer, a relay including an operating coil, a source of electric energy, a circuit for connecting said thermocouple and said coil in series with said source, a circuit for connecting said ccil in series with said source, circuit making-and-breaking contacts for each of said circuits, and means for simultaneously opening and closing said contacts for the iirst and second named circuits respectively and for subsequently opening said contacts for the third named circuit.

.5. 'The combination of a thermocouple, a pyrometer, a circuit for interconnecting said thermocouple and said pyrometer, a relay including an operating coil, a source of electric energy, a circuit for connecting said thermocouple and said coil in series with said source, a circuit for connecting said coil in series with said source, circuit making-and-breaking contacts for each of said circuits, and means for periodically opening 5 and closing said contacts for the first named circuit while closing and opening said contacts for the second named circuit simultaneously therewith and for periodically opening and closing said contacts for the third named circuit respectively subsequently and previously to said opening and closing of the second named contacts.

JOHN T. NICHOLS. 

